Dampers



Jan. 11, 1966 w, M. LOWE ETAL 3,228,339

DAMPERS Filed Sept. 30, 1963 2 Sheets-Sheet l l": I, ,m J

i 1/ 1 l g r z i J fl' I r i W 7 J E \7 E 4 T: 6 L k 1 \L l Jan. 11, 1966 w, M. LOWE ETAL DAMPERS 2 Sheets-Sheet 2 Filed Sept. 50, 1965 United States Patent Ofiice 3,228,38 Patented Jan. 11, 1966 3,228,389 DAMPERS Walter Max Lowe and Frederick Squirrel], London, England, assignors to Thermo-Technical Development Limited, London, England, a company of Great Britain Filed Sept. 30, 1963, Ser. No. 312,629 2 Claims. (Cl. 126285) This invention relates to dampers, e.-g. for the gastight isolation of flues or of equipment connected with fiues.

Such dampers consist of a frame, or frame members, fitted in the flue and of a moving member operable from an open position to a closed position.

Various means have been proposed to render these dampers as gastight as possible. Since this is only practicable to a certain degree, a residual leakage of flue gas around the edges of the closed moving member from the flue part on the one side of the damper to the flue part on the other side of the damper, as a result of the pressure differential, is unavoidable. This residual leakage will tend to increase in service due to distortion, deposits, and for other reasons.

The residual flue gas leakage, even if it could be kept down to a rate which would make it unimportant from the point of view of operational efliciency of a boiler, still has serious consequences for the safety of personnel, and for the operation of power stations. For instance, when flue systems are under positive pressure, any residual damper leakage will let flue gas escape into the boiler house when the boiler is shut down, unless fans are kept running continuously at very considerable cost. Furthermore, when the damper serves to isolate part of a working flue system in order to permit access of repair crews, and the pressure in the flue parts to be isolated is lower than that on the other side of the damper, gas would flow through the residual leakage and impair health and safety of the repair personnel. All these and similar contingencies might enforce a partial or a full shut-down of a power station which, in the case of a large base load station, may well involve the loss of generating capacity for many millions of kilowatt hours equivalent to a very large cost per day.

It is an object of the present invention to overcome these difficulties in an economical manner.

The invention is applicable to a wide variety of dampers such as swivel dampers (that is to say a damper in which the moving member is mounted in the flue so as to swivel about an axis between the open and closed positions), sliding dampers and mushroom dampers but will be described with principal reference to one type, namely, a curtain damper.

In the drawings:

FIGURE 1 is a side elevation;

FIGURE 2 is a section on the line IIII of FIGURE 1;

FIGURE 3 is a section on the line IHHI of FIGURE 1 of a curtain damper according to the invention;

FIGURE 4 is a view similar to FIGURE 3 showing a modification;

FIGURE 5 is a view similar to FIGURE 3 of a further modification incorporating a rigid slide instead of a curtain; and

FIGURE 6 is a similar view to FIGURE 3 of a swivel damper incorporating the invention.

In the FIGURES l to 3 a curtain 1 is wound around a roller 2 mounted by bracket 3a in the top of a frame unit 3 mounted in a grip in the flue 3a. The curtain is arranged to drop vertically through slots 4 in the frame unit being pulled down by a rope 5.

The curtain is fitted with pro-formed heat-resisting alloy spring strips 7 along its sides and 6 along its bottom edge. The preformed heat-resisting alloy spring strips may be long continuous strips or formed of overlapping shorter strips along its side edges.

The side slots 4 restrain the outward spreading strips 7 to form sealed barrier air channels 12 in the closed position of the damper.

The damper frame unit 3 has mounted on it at one end a fan 8 for supplying air at above atmospheric pressure.

The fan communicates with a channel 9 running along the length of the top of the frame and thence to a tube 10 with a valve 11 to communicate with duct 12 on the far side of the curtain. The fan also communicates through tube 10a and valve 11a with the duct 12 on the near side of the curtain. Ducts 12 extend down the sides of the curtain and communicate through spaced apertures 12a with the channels or conduits formed by slot 4 and spring strips 7 at the other edge of the frame.

At the bottom ends ducts 12 communicate with a transverse duct 13 along the bottom of the frame.

Channel or conduit 9 is formed with four spring strips 15 secured to the frame and engaging the curtain to form two sealed channels one on each side of the curtain. The rest of the system can be isolated from it by closing valves 11, 11a so that air cannot enter the flue through ducts 12 when the damper is in its open position.

In operation, when the curtain 1 is in the raised position the joint between the top springs 15 may be suitably sealed off by air pressure from the fan passing along ducts 9. When the curtain is lowered the valves 11 and 11a may be operated to extend the air flow down the side ducts 12 and bottom channel 13 to complete the sealing of the closed damper. Gas flow from duct 12 through the apertures 12a equalizes the pressure in channel 12' and prevents pressure loss along its length.

The excess pressure in the ducts 9, 12 and 13 ensures that leakage will be into the flue and not out of it. Also the excess gas pressure aids the sealing effect of the spring strips, 6, '7 and 15.

When the curtain is rolled up the strips 7 flatten out to roll around the roller.

When the curtain is lowered the spring strips 6 at the bottom edge are guided into the slots 4 by outwardly inclined extensions 4a.

The flexible curtain will adapt itself to any distortions of the frame unit.

FIGURE 4 shows a modified form of the collapsible channel of FIGURE 3 in which a spreader bar 17 yieldingly supported by vertically spaced V-springs 18 aids the spreading of the spring strips 7 into contact with the sides of slots 4.

FIGURE 5 shows a rigid slide 22 in place of the curtain. The slide is shown engaged by springs 23 on each side to form a channel or conduit in the slot 4 which remains closed towards the flue even when the slide is withdrawn.

FIGURE 6 shows a swivel damper member 24 to the edge of which is attached, by means of bolts 25, an abutm-ent member 26 and a flat resilient spring strip 27. Instead of the slot 4 an abutment member 28 and a flat resilient spring strip 29 are attached to the frame 3.

In the closed position spring strip 27 co-operates with abutment 28 and spring strip 2? with abutment 26 t o form a sealed channel or conduit 30, communicating through apertures 12a with duct 12 as before.

Various other modifications may be made in accordance with the invention. Thus, particularly for small sizes of damper, the curtain might be replaced by a box slide in any of the embodiments, that is to say be a rectangular box construction.

We claim:

1. A system for the gastight isolation of fines and equipment connected therewith comprising a flue, a fixed frame member, fitting into the flue, a moving closure member operable from an open position to a closed position generally covering the frame aperture, a conduit between the fixed frame member and moving closure member extending along at least part of the periphery of the frame aperture and apertured along its length on the side of the moving closure member, means forming a passage connecting said conduit to atmosphere, means for sealing said passage from atmosphere when the damper is open, and means including resilient flexible cantilever components on each side of the moving closure member stressed between the edge of the moving closure member and the conduit in the closed position to seal said apertured length of the conduit from the flue, said flexible cantilever components acting in such a direction that their sealing action is increased by increased gas pressure in the conduit whereby an explosion wave on the one side of the moving closure member deflecting the resilient flexible cantilever components on that side and entering the conduit will act to reinforce the sealing action of the resilient flexible cantilever components on the other side and escape via said passage.

2. A system for the gastight isolation of flues and equipment connected therewith comprising a flue, .a fixed frame member, fitting into the flue, a moving closure member operable from an open position to a closed position generally covering the frame aperture, a conduit between the fixed frame member and moving closure member extending along at least part of the periphery of the frame aperture and apertured along its length on the side of the moving closure member, means forming a passage connecting said conduit to atmosphere, means for sealing said passage from atmosphere when the damper is open, fan means to pressurize the passage with a gas at a pressure higher than atmosphere, and means including resilient flexible cantilever components on each side of the moving closure means stressed between the edge of the moving closure member and the conduit in the closed position to seal said apertured length of the conduit from the flue, said flexible cantilever components acting in such a direction that their sealing action is increased by increased gas pressure in the conduit whereby an explosion wave on the one side of the moving closure member deflecting the resilient flexible cantilever components on that side and entering the conduit will act to reinforce the sealing action of the resilient flexible cantilever components on the other side and escape via said passage.

References Cited by the Examiner UNITED STATES PATENTS 1,476,344 12/1923 McGee et al 25l-=-l72 X 2,582,877 1/1952 Mekler 25 l.'l75

FOREIGN PATENTS 536,314 5/ 1941 Great Britain. 802,916 10/1958 Great Britain.

JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L. MATTESQN, Examiner. 

1. A SYSTEM FOR THE GASTIGHT ISOLATION OF FLUES AND EQUIPMENT CONNECTED THEREWITH COMPRISING A FLUE, A FIXED FRAME MEMBER, FITTING INTO THE FLUE, A MOVING CLOSURE MEMBER OPERABLE FROM AN OPEN POSITION TO A CLOSED POSITION GENERALLY COVERING THE FRAME APERTURE, A CONDUIT BETWEEN THE FIXED FRAME MEMBER AND MOVING CLOSURE MEMBER EXTENDING ALONG AT LEAST PART OF THE PERIPHERY OF THE FRAME APERTURE AND APERTURED ALONG ITS LENGTH OF THE SIDE OF THE MOVING CLOSURE MEMBER, MEANS FORMING A PASSAGE CONNECTING SAID CONDUIT TO ATMOSPHERE, MEANS FOR SEALING SAID PASSAGE FROM ATMOSPHERE WHEN THE DAMPER IS OPEN AND MEANS INCLUDING RESILIENT FLEXIBLE CANTILEVER COMPONENTS ON EACH SIDE OF THE MOVING CLOSURE MEMBER STRESSED BETWEEN THE EDGE OF THE MOVING CLOSURE MEMBER AND THE CONDUIT IN THE CLOSED POSITION TO SEAL SAID APERTURED LENGTH OF THE CONDUIT FROM THE FLUE, SAID FLEXIBLE CANTILEVER COMPONENTS ACTING IN SUCH A DIRECTION THAT THEIR SEALING ACTION IS INCREASED BY INCREASED GAS PRESSURE IN THE CONDUIT WHEREBY AN EXPLOSION WAVE ON THE ONE SIDE OF THE MOVING CLOSURE MEMBER DEFLECTING THE RESILIENT FLEXIBLE CANTILEVER COMPONENTS ON THE SIDE AND ENTERING THE CONDUIT WILL ACT TO REINFORCE THE SEALING ACTION OF THE RESILIENT FLEXIBLE CANTILEVER COMPONENTS ON THE OTHER SIDE AND ESCAPE VIA SAID PASSAGE. 